Elephants Toothpaste.

Elephants toothpaste was part of the Original Hot Stuff Roadshow. The experiment hasn't changed much, although the ceiling in the megalab has had some... intricate paint work provided by some elephants toothpaste mishaps.

The Science Behind it:

The Elephants Toothpaste Reaction is the decomposition of Hydrogen Peroxide into water and Oxygen.  Hydrogen Peroxide (H202) will naturally decompose in the presence of oxygen, however the reaction is so slow that it is barely noticable. We use the catalyst Potassium Iodide to speed up the reaction. A catalyst speeds up a reaction but is not used up in the result. So if we added more hydrogen peroxide to the bottle, the reaction would keep going.  In this case, the potassium iodide is acting to rip the H202 apart. 

The products of this reaction are obviously Oxygen and Water.  We add dish soap in order to trap the oxygen that is rapidly produced in bubbles. This results in a whole lot of bubbles being forced out of the small neck of the bottle really quickly, hence the spout. This reaction is an exothermic reaction, which means it releases heat, as seen by the steam given off which is the water boiling. This means that the reaction is at least 100 degrees celsius so don't touch it.  

2 H202 --> O2 + 2 H2O